A Monte Carlo simulation study for cosmic-ray chemical composition measurement with Cherenkov Telescope Array

Our Galaxy is filled with cosmic-ray particles and more than 98% of them are atomic nuclei. In order to clarify their origin and acceleration mechanism, chemical composition measurements of these cosmic rays with wide energy coverage play an important role. Imaging Atmospheric Cherenkov Telescope (IACT) arrays are designed to detect cosmic gamma-rays in the very-high-energy regime ($\sim$TeV). Recently these systems proved to be capable of measuring cosmic-ray chemical composition in the sub-PeV region by capturing direct Cherenkov photons emitted by charged primary particles. Extensive air shower profiles measured by IACTs also contain information about the primary particle type since the cross section of inelastic scattering in the air depends on the primary mass number. The Cherenkov Telescope Array (CTA) is the next generation IACT system, which will consist of multiple types of telescopes and have a km$^2$-scale footprint and extended energy coverage (20 GeV to 300 TeV). In order to estimate CTA potential for cosmic ray composition measurement, a full Monte Carlo simulation including a description of extensive air shower and detector response is needed. We generated a number of cosmic-ray nuclei events (8 types selected from H to Fe) for a specific CTA layout candidate in the southern-hemisphere site. We applied Direct Cherenkov event selection and shower profile analysis to these data and preliminary results on charge number resolution and expected event count rate for these cosmic-ray nuclei are presented.Comment: All CTA contributions at arXiv:1709.03483 , Proceedings of the 35th International Cosmic Ray Conferenc

Recent Results from the CANGAROO 3.8 m Telescope

Abstract. We observed the shell-type supernova remnant (SNR) RX J1713.7–3946 and the X-ray binaries Cen X-3 and Vela X-1 at TeV energies in 1998 using the CAN-GAROO 3.8 m telescope. Preliminary results of data analyses on these objects are summarized here. We also estimated a spectrum of the Vela pulsar region using 116 hr data taken by the 3.8 m telescope during 1994 and 1997. The two data sets having different mirror reflectivities give consistent results and the photon index of the best-fit power-law spectrum is −2.4 ± 0.2

A Monte Carlo simulation study for cosmic-ray chemical composition measurement with Cherenkov Telescope Array

Our Galaxy is filled with cosmic-ray particles and more than 98% of them are atomic nuclei. In order to clarify their origin and acceleration mechanism, chemical composition measurements of these cosmic rays with wide energy coverage play an important role. Imaging Atmospheric Cherenkov Telescope (IACT) arrays are designed to detect cosmic gamma-rays in the very-high-energy regime ($\sim$TeV). Recently these systems proved to be capable of measuring cosmic-ray chemical composition in the sub-PeV region by capturing direct Cherenkov photons emitted by charged primary particles. Extensive air shower profiles measured by IACTs also contain information about the primary particle type since the cross section of inelastic scattering in the air depends on the primary mass number. The Cherenkov Telescope Array (CTA) is the next generation IACT system, which will consist of multiple types of telescopes and have a km$^2$-scale footprint and extended energy coverage (20 GeV to 300 TeV). In order to estimate CTA potential for cosmic ray composition measurement, a full Monte Carlo simulation including a description of extensive air shower and detector response is needed. We generated a number of cosmic-ray nuclei events (8 types selected from H to Fe) for a specific CTA layout candidate in the southern-hemisphere site. We applied Direct Cherenkov event selection and shower profile analysis to these data and preliminary results on charge number resolution and expected event count rate for these cosmic-ray nuclei are presented

Effect of the uncertainty in the hadronic interaction models on the estimation of the sensitivity of the Cherenkov telescope array

International audienceImaging atmospheric Cherenkov telescopes (IACTs) are ground-based indirect detectors for cosmic gamma rays with energies above tens of GeV. The major backgrounds for gamma-ray observations in IACTs are cosmic-ray charged particles. The capability to reject these backgrounds is the most important factor determining the gamma-ray sensitivity of IACT systems. Monte Carlo simulations are used to estimate the residual background rates and sensitivity of the systems during the design and construction phase. Uncertainties in the modeling of high-energy hadronic interactions of cosmic rays with nuclei in the air propagate into the estimates of residual background rates and subsequently into the estimated instrument sensitivity. We investigate the influence of the difference in the current hadronic interaction models on the estimated gamma-ray sensitivity of the Cherenkov Telescope Array using four interaction models (QGSJET-II-03, QGSJET-II-04, EPOS-LHC, and SIBYLL2.3c) implemented in the air shower simulation tool CORSIKA. Variations in background rates of up to a factor 2 with respect to QGSJET-II-03 are observed between the models, mainly due to differences in the π 0 production spectrum. These lead to ∼30% differences in the estimated gamma-ray sensitivity in the 1–30 TeV region, assuming a 50 h observation of a gamma-ray point-like source. The presented results also show that IACTs have a significant capability in the verification of hadronic interaction models